Safety device for bucket elevators



Oct. 24, 1961 P. D. HINDERAKER 3,005,540

SAFETY DEVICE FOR BUCKET ELEVATORS Filed D60. 24, 1957 2 Sheets-Sheet 1 54 aao RC 3'? 229V AC uo'fiC a Phlllp a H/nderaker INVEN TOR.

con W 3% Oct. 24, 1961 P. D. HINDERAKER 3,005,540

SAFETY DEVICE FOR BUCKET ELEVATORS Filed Dec. 24. 1957 2 Sheets-Sheet 2 N A a c 64 Philip 0. Hinderaker I? IN VEN TOR.

/o0 BY @Zuaap WW 29% Unit This invention relates generally to an electromechanical safety device for bucket elevators used in the automatic feeding of grain. 1

The particular novelty of this invention lies in the alleviation of one of the most irritating problems in the operation of a country grain elevator. The problem involves the-choke up of the bucket elevator resulting from opening the grain inlet or slide too far, and thereby permitting too much grain to flow from the pit into the boot where it is picked up by the buckets on a moving belt, and carried to the top of the elevator. The tendency is to keep opening the slide in order to have the grain carried away at the maximum speed. It often happens that the pressure :of the grain is too great for the motor powering the bucket elevator belt, and stoppage occurs before the fiow of the grain into the boot can be stopped. When this happens, the disagreeable task of removing the grain from the boot must be undertaken beforethe movement of the bucket elevator belt can be reestablished. The .novel means of this invention lies in the utilization of the sensing of an increase in motor current driving the belt and the electrical circuitry which responds to this sensing to close the outlet from the grain reservoir or pit. Former systems all utilized the-speed of the belt as an indication of the overload on the belt. It has been found that by utilizing the increase in current of the driving motor upon overload of the belt rather than the speed of the belt itself as sensing means results in a quicker and more efiicient safety device.

The principal object of this invention therefore is to provide a novel and efiicient grain elevator safety device.

It is a further object of this invention to provide novel sensing lmeans to actuate the safety device.

It is a still further object to provide a safety device which is inexpensive to manufacture, reliable, and is chap acterized by its simplicity and accompanying ease of repair. 1

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more-fully hereinafter described and claimed, reference being bad to the accompanying drawings forminga part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 shows a schematic diagram of one embodiment of the invention clearly showing the drive motor, sensing means, and actuating means for closing the reservoir or pit outlet;

FIGURE 2 shows another embodiment of the invention utilizing a reversible motor and accompanying threaded shaft means to close the reservoir or pit outlet;

FIGURE 3 shows still a further embodiment of the invention;

FIGURE 4 shows still another form of the invention utilizing the same basic principle; and

FIGURE 5 is a diagrammatic view illustrating a typical system into which the invention may be incorporated.

Referring initially to FIGURE 1, numeral 1 designates a three-phase alternating current induction motor for driving a moving belt 3. It is to be noted that the particular type of motor to be used for driving the belt is not important and most any motor of the proper horse power could be used. The three-phase lines are designated as A, B and C and it is to'be noted that phase line C has interposed therein a primary coil 2 of transformer 4. Inductively coupled to the primary coil 2 is a secondtates Patent energy source while fixed contact 22 is connected through solenoid coil 24 to the second side of the electrical energy source. An armature 26 is disposed within solenoid coil 24 and it possesses an angularly related end portion 28. This portion 28 is adapted to cooperate with member 30 which is fixedly connected to triangular support 32. At right angles to member 30 is a holding member 34 which is also fixedly connected to triangular support 32. The triangular support 32 is pivotally mounted. at pin 36 to a support (not shown).

Fixedly mounted in the grain elevator is a collar member 38 containing a shaft 40 within. Said shaft-has a compression spring 42 attached to it at aperture 44.

The opposite end of spring 42 is attached to the permanently aflixed collar member 38- at 46. Cooperating with member 34 is a toothed portion48 on shaft 40. On the lower end of shaft 40 is afiixed a door 50 which is adapted to cover the doorway 52 to a pit or reservoir 53 for grain.

In operation of the embodiment of FIGURE 1, upon an overload of buckets carried by the driven belt, the motor 1 will draw greater current through phase lines A, B and C. -As a greater A.C. current is drawn through phase line C, it will of course pass through primary coil 2 and be induced in secondary coil 6 and thereby increase the DC. output across points 1212. ,This increase in voltage across points 1212 will cause an increase in current through relay 14. Contacts 20 and 22, normally open, will closeupon the increased current through relay 14. It is mentioned here that variable resistor 16 can be adjusted to cause the contacts 20, 22 to close at a particular degree of overload current through primary coil 2; The closure of contacts of 20 and 22 activate solenoid 24 drawing armature 26 from its solid to its dotted position shown in FIGURE 1. The movement of the armature 26 of course forces member 30 to its dotted position and triangular support 32 to pivot around pin 36. Likewise, member 34 assumes its dotted position and emerges from itscooperating relationship with toothed portion 48 of shaft 40. vThe member 34 has up to this time been holding shaft 40 in the position shown in FIGURE 1. Upon the rotation of 34 about pin 36, the shaft 40 will assume its dotted position due to the compressive spring action of spring member 42. The door 50 fixedly attached to shaft 44 will fall into place opposing doorway 52 to the grain reservoir 53 and therefore stop the flow of grain to the buckets carried by the elevator. The sequence is rapid enough to prevent any overflow of grain 7 FIGURE 2 shows a device similar to FIGURE 1 and is identical up to the point of the electro-magnetic relay 14. Instead of thesingle fixed contact utilized in FIG- URE 1 two fixed contacts 54 and 56 are shown. A compression spring 58 biases movable contact member 60 to a position in contact with fixed contact member 56; Fixed members 54 and 56 are connected to terminals 60 and 62 of a reversible A.C. motor 64. Movable contact 60 is connected to th live side of a volt A.C. distribution line. A third terminal66 on reversible motor 64 is connected to the other side of the A.C. line. The motor 64 is operatively connected through well known means to threaded shaft 66 which has a door 50 fixedly mounted thereon which is adapted to cover doorway 52.

.Theoperation of FIGURE 2 is very similar to that explained. above. for FIGURE 1 Themechanical overload on the moving belt will cause the driving motor 1 to draw an increased current through the phase lines A, B and' C and: therefor an increased: current isinduced in the secondary coil 6 likewise causing a. greater current through relay 14 In normal operation the current through relay 14 iszsufiicient to hold themovable contact 60. in theneutral position shown in FIGURE 2. That is, the movable. contact 60.' should notftouch either fixed contact. 54 or 5.6 while the moving belt is under normal load. Therefore, the normal current through relay 14' must. overcome: the bias spring 58'which wouldnormally bias movable contact 60'to a position touching fixed con tact: 56. When the belt is either overloaded or underloaded,. the current through relay 14 will pull movable contact; 60. into. contact with fixed contact member 54 or effectively relinquish all force on the movable contact member whereby bias spring 58 will bring it in contact with fixed. contact 56. It canbe seen that fixed contact members 54 and 56 lead to terminals on a reversible motor 64 and movable contact 60 is connected to the live side of. an A.C. line. A third contact on the motor is connected to the second side of the AC. line. As explained above the motor is operatively connected to the threaded shaft. 66 to selectively move it up or down depending onzthe rotational direction of the motor. In summary'therefore, upon an overload of the belt 3 the movable; contact member 60 will be brought into contact with fixed contact member 54 which will actuate the motor 64 through terminal 60 and cause the shaft 66 to be lowered, therebystopping flow of grain into'the buckets on the moving belt 3; Likewise a decrease of theload on; the: moving belt will cause a decrease in current to thelmotor and movable contact 60becomes connected to fixed contact member 66 and the motor 64 will be actuated throughterminal 62. Threaded shaft 66 will in this case beraisedto increase the grain flow to the buckets on the moving belt 3. 7

FIGURE 3' shows a still further embodiment of the invention where numeral 1 again designates the threephasemotor and thephase hnes are shown as A, B and C. This embodiment represents a variation; from that of FIGURE 1 in that the relay controlled door closing. circuit is energized, not by an independent source of current but by asource derived from one of the three-phase power lines to: motor 1 other than the power line to which the relay solenoid is operatively connected. In this embodiment relay coil 70' is shown operatively interposedinphase line C by asuitable D.C. rectifier circuitv 71 such as shown for example in connection with FIGURES 1 and 2. The relay coil 70 operates movable contact 72 which operatively connects phase hne B through a rectifier to solenoid 7'4 and to the neutral .line- N'. Within. solenoid coil 74 is an armature 76 to which is attached a compression-spring 7 8 which in turn ismounted'on afii'xed member'80. Mounted on the armature 76Zisahandl'e 82 for-manually slidabl'y moving armature 76 against the force-otferedby tension spring 78. One end of armature 76 cooperates with a toothed portion'84' on shaft 86' which fits through a fixed collar 88. Fixedly mounted on the collar 88 and the shaft 86 is a compression spring 90 which tends to force the shaft 86 downwardly through collar 88 Attached to the bottom of shaft 86 is adoor 50 ad'apted to cover a doorway S2 in a bin or grain reservoir.

I'n'the normal operation of this embodiment a current will flowthrough relay coil 70" which will not be sulficient to move contacts 72. Normally then; contact 72 will; be-cl'osed and a current will flow through solenoid coil 74 forcing armature '16- toward shaft 86 against the tensile strength offered by spring'78i While the belt is running therefore, shaft 86 is raisedopening doorway 52 to feed grainto the buckets on the moving belts. Handle 82 moves the armature 76' into engagement with shaft 86' and holds the shaft and thereforethe' door 50 in any one of a desired number of positions. As long as normaloperation continues the solenoid will be energized and armature 76 will hold shaft 86 in the desired positions. Upon an overload of the belt 3 and corresponding increase in motor current, relay coil 70 will open movable contact '72- and therefore cut off the electrical energy supplied to. solenoid coil 74-. Under these circumstances compression spring 78' will hold the. armature out of contact with shaft. 86 causing compression spring 90 to force shaft 86. and attached door 50- downwardly to lock doorway 52 and stop the grain flow to the buckets on the moving belt 3. When the main switch is opened or if the powershould fail; the slide will automatically drop, thus cutting off the flow'of grain tothe bucket elevator.

FIGURE 4 shows another embodiment of the invention where numeral 1 again designates a three-phase driving motor to actuate a moving belt. This embodiment represents a variation from that of FIGURE; 2- in which the reversible motor 64 is energized not by an independ-- ent power source but by current derived from the threephase power lines. Other variations from FIGURE 2' also: characterize thelatter embodiment as will be hereafter described. ln this embodiment two electro-magnetic coils 92 and 94 are operatively interposed in phase lines A- and C through rectifier circuits )8 and 95', respectively. A- movable contact 96isresponsive to the current through electromagnetic coil 92. The movable contact- 96coopcrates with fixed contact 98 such that they are normally closed. The movable contact 96- operatively proceeds to the phase line A on the side ofmain switch 100 closer to the mainel'ectrical source to provide one source of current for themotor 64. A- movable contact'1'02 is responsive to the current through electro-magnetic coil 94 and isoperatively connected to thephase line B on the side of main switch' 100- away from the electrical source to provide a second source of current for the motor 64. The movable contact 102' cooperates with fixed contacts 104-a1id 106. A compression-spring 108 normallybiases movable contact 104 into electrical contact with fixed' contact 104. Fixed contact 104 proceeds to a. limit switch 110'- having a pivotally connected contact- 112 which normally cooperates electrically with fixed contact 114 which proceeds to terminal 116 on reversible motor 64. Fixed contact 106 proceeds electrically to limit switch 118 having a pivotal contact 120 therein which cooperates electrically with fixed contact 122. Pivotal" contact 120 proceeds electrically to terminal 117 on reversible motor 64. A third" terminal 124 on'the reversible motor 64 is directly electrically connected to the neutralline; A projection-126 011 the shaft 66 is socon-- structed' that it will open the pivotal contacts'11'2 and 120 in limit switches 110' and 118: as the threaded shaft pro ceeds vertically.

In operation; an overload on motor 1 causesan increase of current through electro-magnetic coil 94. An increase current in coil 94 will cause movable contact 102 to move into a position so that it electrically contactsfixed contact 106-to energize the reversible motor 64 from-thephas'e line B, themovable contact 102, the fixed contact 1416, the contact 122; the pivotal contact 120 tothe terminal 117011- the motor 64.- This overload current more thanlikely has been due to an overload on the belt 3 therefore necessitating reduction in the load carried by the belt 3. The energization of the reversible motor 64 betweenterminals 117 and 124 will cause the threaded shaft to movedownwardly'until-the door 50 impedes the flow of grain-tosuch anextent that the belt load and current load are reduced and the electrical connection between 106 and 1025s broken.

Reduction inthe load on the belt and likewise reductionin the current through the motor will cause the electro-magnetic coil 94 to release the movable contact 102 which willthen; electrically contact fixed contact 104 due to the force exerted by spring 108. Upon this 00- currence; the reversible motor 64 will. be energized between terminars I16 and 124 causing the threaded shaft 66 to carry the door 50 upwardly allowing greater flow of grain onto the belt and so increasing the load until the electromagnetic coil 94 will draw movable contact 102 to its neutral position as shown in FIGURE 4. As will be apparent from the drawing, the extent of the movement of shaft 66 is limited by the projection 126 which opens the electrical circuit to the motor by opening the connection between contact 122 and pivotal contact 120 or the connection between contact 114 and pivotal contact 112.

The electromagnetic coil 92 and contacts 96 and 98, provide a safety aspect for this embodiment. That is, if the main switch 1% were opened, an electrical connection will result from the live side of phase line A through cont-act 96, 98, 122, 126 to terminal 117 of reversible motor 64. Therefore, it is apparent that whenever the main switch tea is open the door is of necessity stopping the grain flow to the belt 3. We see then that the belt 3 cannot be stopped with the door 59 open. Of course, when the belt 3 is running, the current through 92 is sufficient to electrically disconnect the contacts 96 and 98.

It should further be apparent that the refinements introduced in FIGURE 4, that is, specifically the coil 92 and cooperating contact 96 and the limit switches 110 and 118 which cooperate with projection. 126 could'be incorporated in the embodiment of FIGURE 2.

FIGURE 5 illustrates a portion of a typical bucket elevator system wherein the conveyor belt 3 driven by motor 1 carries grain 5 from the grain reservoir 53 through the doorway 52. Door 50 controls the grain output through the doorway 52 as previously explained;

From the foregoing, the construction and operation of the device will be readily understood and further explanation is believed to be unnecessary. However, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A safety device for grain elevators having a carrying belt comprising a motor, wirm connecting said motor to a source of electrical energy, said motor drivingly connected to said carrying belt, electrical sensing means connected to at least one of said wires and responsive to a predetermined change of current therein, and electro mechanical means operatively connected to said sensing means for incrementally controlling a flow of grain to said belt and safety means energized by said source of electrical energy for positive interruption of flow of grain when said source becomes disconnected from said motor.

2. A safety device for grain elevators having a carrying belt comprising a motor, wires connecting said motor to a source of electrical energy, said motor drivingly connected to said carrying belt, an electromagnet interposed in one of said wires, switching means having a plurality of contact positions located proximate to said electromagnet and responsive thereto, a second electric motor, said second motor constructed to be able to reverse its rotational direction dependent on the electrical energy supplied thereto, a second source of electrical energy, and means connecting said switching means to said second source and said second motor to operate said second motor in selective directions dependent on the quantity of current in said electromagnet, said second motor being operatively connected to a movable rod so that said rod will move in a selective manner dependent on the direction of rotation of the second motor, and a door on said rod to control a grain outlet to said carrying belt, a second electromagnet interposed in a second of said wires, electrical contacts responsive to said second electromagnet to allow a selective directional energization of said second motor when a current flows through said second wire but to automatically energize said second motor to close said door upon a cessation of current in said second wire.

3. A safety device for grain elevators having a carrying belt comprising a motor, wires connecting said motor to a source of electrical energy, said motor drivingly connected to said carrying belt, an electromagnet interposed in one of said wires, switching means having a plurality of contact positions located proximate to said electromagnet and responsive thereto, a second electric motor, said second motor constructed to be able to reverse its rotational direction dependent on the electrical energy supplied thereto, a second source of electrical energy, and means connecting said switching means to said second source and said secondmotor to operate said second motor in selective direct-ions dependent on the quantity of current in said eleotromagnet, said second motor being operatively connected to a movable shaft so that said shaft will move in a selective manner dc pendent on the direction of rotation of the second motor, and a door onsaid shaft to control a grain outlet to said carrying belt, a projection on said shaft, limit switches, said limit switches electrically connected in said second motor circuit and located proximate said shaft projection whereby cooperation between said projection and said limit switches cuts off electrical energy to said second motor upon an extreme movement of said shaft, a second electromagnet interposed in a second of said wires, electrical contacts responsive to said second electromagnet to allow a selective directional energization of said second motor when a current flows through said second wire but to automatically energize said second motor to close said door upon a cessation of current in said second wire.

4. A safety device for grain elevators or the like employing a grain delivery control gate and a multiphase delivery conveyor motor, comprising, a main power source operatively connected to said motor by a plurality of power lines, circuit means energized by a secondary power source derived from one of said power lines and operatively connected to said control gate for control thereof, relay control means operatively connected to a second of said power lines for conditioning said circuit means in response to a predetermined flow of current in said one power line to permit constant flow of grain through said control gate in response to operation of the motor and means responsive to a variation of current flow from said predetermined flow to cause the relay control means to recondition the circuit means for control of the control gate to inversely vary the flow of grain in accordance with said current flow, said circuit means including a reversible motor means operatively connected to the control gate and conditioned by the relay control means to remain inoperative and reconditioned by the relay control means to rotate in opposite directions in accordance with the variation in power line current flow from the determined flow, and means operatively connected to a third of said power lines and to said reversible motor means for operation thereof in a gate closing direction in response to disconnection of said power lines from the conveyor moto References Cited in the file of this patent UNITED STATES PATENTS 1,777,670 Hausman Oct. 7, 1930 1,842,919 Simmons Jan. 26, 1932 2,336,434 Wu-rzbach Dec. 7, 1943 2,343,722 Wagner Mar. 7, 1944 2,697,556 Turner Dec. 21, 1954 

